BI metal spare blade for 300 mm (12″) hacksaws. Blade length 300 mm, 24 teeth per inch. Iron dumbbells made of bi-metal are significantly more durable than ordinary iron dumbbells and it is almost impossible to break them. Precision-ground teeth improve blade durability and performance when sawing most hard materials. Suitable for e.g. for aluminium, bronze, copper, brass, hard plastics, cast iron, steel and stainless steel.